Photosynthesis- Part 2

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What are limiting factors?
Factors that affect the rate of photosynthesis
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What 5 factors affect the rate of photosynthesis?
Light intensity, amount of CO2 amount of water, temperature, availability of chlorophyll, electron carriers, enzymes
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What limits the rate of photosynthesis?
The factor that's present in the least favourable amount (limiting factor0
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What unit measures the rate of photosynthesis?
Lux
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Unit for light intensity?
Arbitrary units (a.u.)
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What is light intensity?
The level of light
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Why is light needed for photosynthesis?
Provides energy for the 1st stage that produces ATP and NADP for the 2nd stage) & opens the stoma for the transpiration of water for photolysis
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What happens to the GP concentration when the light intensity is dim?
GP levels increase
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Why?
They can't be reduced due to low levels of NADPH and ATP
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What happens to the concentration of TP?
They decrease
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Why?
Because GP isn't reduced
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What happens to the concentration of RuBP?
It decreases
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Why?
Because GP isn't being reduced and RubP isn't being regenerated from TP
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What happens if the concentration of carbon dioxide falls below 0.01%?
RuBP can't accept it and accumulates, GP and thus TP can't be made
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What are the limitations of measuring the rate of photosynthesis based on how much O2 is produced?
Some of the O2 is used by the plant for respiration + there may be some dissolved nitrogen in the gas collected
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What apparatus can be used to measure the factors affecting photosynthesis?
A photosynthometer
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Why is the calvin cycle senstitive to temperature?
It involves many enzyme-catalysed reactions
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In what conditions does the rate of photosynthesis increase?
From low temperatures to 25-30C; if there's enough light, water and CO2
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What happens in the calvin cycle at temperatures above 30C?
Growth rates decline due to photorespiration: oxygen competes with carbon dioxide for Rubisco's active site
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What happens in the calvin cycle at temperatures above 45C?
The enzymes involved in photosynthesis may denature
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What is water stress?
The condition a plant experiences when water supply becomes limited
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Other cards in this set

Card 2

Front

What 5 factors affect the rate of photosynthesis?

Back

Light intensity, amount of CO2 amount of water, temperature, availability of chlorophyll, electron carriers, enzymes

Card 3

Front

What limits the rate of photosynthesis?

Back

Preview of the front of card 3

Card 4

Front

What unit measures the rate of photosynthesis?

Back

Preview of the front of card 4

Card 5

Front

Unit for light intensity?

Back

Preview of the front of card 5
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